Angiogenesis is the growth of new capillary blood vessels, and is a critical component of solid tumor growth (Folkman, N. Engl. J. Med. 285:1182 (1971)). Targeted anti-angiogenic therapy for metastatic breast cancer with bevacizumab, a monoclonal antibody to vascular endothelial growth factor (VEGF), has shown efficacy in patients with metastatic breast cancer (Miller, E2100 Study. Scientific session on monoclonal antibody therapy in breast cancer. Ann. Mtg. Am. Soc. Clin. Oncol. Aug. 29, 2005) and validated the approach of anti-angiogenesis therapy for this disease. Although VEGF is one critical growth factor involved in breast cancer angiogenesis (Schneider et al., Nat. Clin. Pratt. Oncol. 4:181 (2007)), a more detailed understanding of the assortment of genes that are expressed in breast tumor vessels may facilitate the development of novel molecularly targeted antiangiogenic agents.
Several studies have established evidence to suggest that blood vessels supplying tumors express genes not shared by blood vessels that reside in normal tissues (Buckanovich et al., J. Clin. Oncol. 25:852 (2007); Madden et al., Am. J. Pathol. 165:601 (2004); Parker et al., Cancer Res. 64:7857 (2004); St. Croix et al., Science 289:1197 (2000)). St. Croix et al. used a tissue dissociation and cell immunopurification approach to isolate tumor and normal endothelial cells, and then compared gene expression patterns of endothelial cells derived from one colorectal cancer and normal colonic mucosa from the same patient (St. Croix et al., Science 289:1197 (2000)). Using serial analysis of gene expression, this analysis identified 46 transcripts, named tumor endothelial markers (TEMs), which were significantly up-regulated in tumor compared with normal endothelium. Using a similar method, Parker et al. isolated endothelial cells from two human breast tumors and one normal reduction mammoplasty and identified genes that were differentially expressed compared to normal breast tissue (Parker et al., Cancer Res. 64:7857 (2004)). This study identified 30 breast tumor vascular genes, of which HEYL and PRL3 were confirmed to be localized in endothelium by in situ hybridization. These studies have also shown tumor specific differences in tumor endothelial markers between colon, breast, and brain tumors. Buckanovich et al. subsequently used laser capture microdissection of vessel cells from ovarian cancer and normal ovaries and identified 70 differentially expressed TEMs (Buckanovich et al., J. Clin. Oncol. 25:852 (2007)).
Gene expression studies using DNA microarrays have identified several distinct breast cancer subtypes (Perou et al., Nature 406:747 (2000)) that differentiate breast cancers into separate groups that differ markedly in prognosis (Sorlie et al., Proc. Natl. Acad. Sci. USA 98:10869 (2001)). The intrinsic subtypes include 2 main subtypes of estrogen receptor (ER) negative tumors: Basal subtype (ER negative and Her2/neu negative) and Her2/neu subtype (Her2/neu positive and ER negative); and an ER positive (luminal subtype). Given that TEMs differ between tumor types, and that breast cancers are molecularly heterogeneous, it is desirable to determine whether TEMs differ within the different molecular subtypes of breast cancer.
The present invention addresses previous shortcomings in the art by providing novel angiogenesis targets that can be used for diagnostic and therapeutic methods.